Turbochargers for diesel engines control the amount of turbo boost by controlling the flow of exhaust gas onto the turbine blades. Such control is accomplished by an internal actuator that opens and closes a set of vanes that are collectively held by a unison ring. A linear actuator pushes on a slot in the unison ring, which is constrained on its inside diameter by a machined feature on the turbocharger center housing. The constraint causes the linear motion to be converted to rotational motion.